Preparation of an improved hydrocarbon resin



Aug. 28, 1951 J. D. GARBER ETAL PREPARATION oF AN IMPROVED HYDRocARBoN RESIN Filed July 6, 1946 3 Sheets-Sheet 1 Si r3? .TQ @QNWMI nventors CLttov-rieg ug. 28, 1951 J, D, GARBER ETAL 2,565,960

PREPARATION OF AN IMPROVED HYDROCARBON RESIN Filed July 6, 1946 3 Sheets-Sheet 2 Aug. 28, 1951 J. D. GARBER ETAL PREPARATION oF AN IMPRovED HYDROCARBON RESIN 3 Sheets-Sheet 3 Filed July 6, 1946 aina 143.5@ (IPIQJQL m mv Il... -..iw H E bnn,

UZ-J duk() aina.

.Tm mm QN. k

k3 1.22am...

NN.. m

N N uw aina. 05. .uni

mf@ lEQ2 umovmw dui@ mm. m05, 0...@ (IPI 2 Patented Aug. 28, 1951 PREPARATION F AN IMPROVED HYDROCARBON RESIN I John D. Garber, Cranford, and David W.

Roselle, vN. J.,

Young,

.assignors to Standard Oil Development` Company, a. corporation of Delaware Application July, 1946, Serial No. 681,684

yThis invention relates to ole'nic polymers; re-

lates particularly to the production ol clear, lightcolored `polymers, of high solubility, .and relates especially to means for clarifying polymer resins and removing therefrom insoluble cross-linked material.

It has been found possible to produce an extremely valuable synthetic or polymeric resin from mixtures of .mono ole'ns and .multi olefins in Which mixtures there may be present `from 3D percent to 80 percent of a multi olein vsuch Vas butadiene or other multi olefin having from 4 to 14 carbon atoms per molecule with the remainder of the polymerizate mixture consisting of a mono olefin having from 5 to about 20 carbon atoms, or a normal olen having .from 3 to 20`.carbon atoms, by the application to the mixture of .Ja Friedel-Crafts catalyst .at temperatures ranging from about C. to 30 C. to ,produce a resin which is notan .elastomer but is a hard, solid, hydrocarbon-soluble substance having many of the characteristics ofthe natural varnish gums and resins. However, dliculty hasbeeh encountered in the production of .resins of satisfactory quality, because of the unavoidable Droduction during the polymerization of Va small amount of cross-linked material or eel which is found to ybe vinsoluble in many solvents, vineluding the paint and varnish oilsand solvents. This insoluble, cross-linked gel material .is objectionable for most uses to which the resin 'is put, since it interferes with the clarity of the finished varnish. In addition, it is objectionable in molding compositions because of the change ncharacteristics entailed. s

It is now found that thiscross-linked material can be removed from a solution of theresin by a combination of the steps of .settling the resin solution to remove the larger particles of crosslinked material, and the residual traces can be iiltered out by the use of :filter aids, even though the particles tend to be -solvated and slimy. The settlingl properties of the cross-linked material are most unexpected, since it is the Vsame polymer in which several molecules are held together by cross-linkage through unsaturations and it is most unexpected that it should show a difference in specc gravity. Furthermore, while the material is insoluble, it is solvated and slimy in character, and it is most unexpected to nd that the slimy solvated material could be caught on a filter.

Thus the invention polymerizes a diolen such as butadiene in proportions from 30% to 80% with a mono olefin such as di-isobutylene in proportions from 70% to 20% at temperatures within the range between +10 C. and -30 C. by the application thereto (in the presence of a diluent such as liquid propane or butane, if desired) of a Friedel-Crafts catalyst such as aluminum chloride in solution n ethyl or methyl chloride or VAllrz in solution in hydrocarbons such as butane,

hexane, or the like to yield a solution of resin r2 Claims. (Cl. 260-85.3)

in unpolymerized dlolen, :nonoole`iin, catalyst solventand'diluent.

, After the polymerization 'reaction has been vcarried to the desired stage, the 'reaction'inixtureis washed repeatedly 'with `water or with a very mild alkali such as a sodium bicarbonate solution and then, with further repeated washings of water, until a condition of neutrality is obtained; that is, a pH of about 7. The washed material is then passed through a settling chamber in 'which the last traces of water' are settled out and removed, and 'in which a substantial amount of the crosslinked insoluble material settles into a sludge, leaving av supernatant layer of'polymer solution containing considerably reduced amounts Yof insoluble polymer. `This layer of 'solution is `then mixed with a nlter ald such as diatomaceous earth and pumped under'y substantial pressure through 'a llter press, the plates lof which have been pre-coated -with 'a layer of simll'arrlt'er ald. 'I'he solution is delivered from the illterf'ln Aa crystal clear condition, 'substantially completely free from insoluble material.A The polymer is 'then recovered from the solutionln'any "desired manner such as by delivery to and .through a steam-jacketed Monel metal coil, as is shown in our copending applcationrserial No. 662,693, filed April 17, 1946, now U. Patent 2,507,100,

Alternatively, all ofthe insoluble material or gel maybe nltered out without the settling step, or the gel `may be .removed by centri'fuging, which, if properly conducted, yields a crystal clear, sparkling solution of high quality, froml which the polymer is readily 'recovered by hashing through a steam-jacketed coil, or 'by vacuum treatment or by the other nleans. Alternatively, settling alone may be used, especially in' the presence of a rapid settling nlter aid. As another alternative, it is also possible to clarify the material by allowing it 'to percolate through a lter bed, a good grade of 'gel-free 'polymer' solution being vobtainable thereby. After clarification, the polymer' solution is conveniently recovered by flashing. through va steam-jacketed Monel metal coll or by evaporation of the solvent in vacuum at a slightly elevated vtemperature. Other objects and details of the invention will be apparent from the .following description when read in connection with the accompanying drawings, in which:

Figure 1 is a diagrammatic representation of apparatus for the polymerizatiomltration, 'and flashing' of the polymera'cco'rding to the present invention;

Figure 2 is a diagraniniaticv representation of apparatus for the polymerization', centrifugal clariiication and flashing of thepolyiner solution; and Q Figure 3 is a diagrammatic representation of apparatus for the polymerization, percolation-nh tration and flashing of claried resin' solution.

'The raw material for the present invention is a low temperature resin prepared from a multi 3 olefin and agmo'no`Y olefin. The preferred multi olefin is butadiene, but any substituted butadiene or any multi olefin having more than one double linkage is useable; including such substances as isoprene, piperylene, the several dimethyl butedienes, dimethallyl, inyrcene, divinyl benzene, cyclopentadiene, hexatrienefmono vinyl acetylene, allo-ocymene, and the like, any multi olefinic substances having two or more carbon to carbon double linkages per molecule, .and from 4 to lli carbon atoms being useful.

This material is copolymericed with a mono olenor mixtures of mono olenns such as propylene, or normal butylene; all of the pentenes, hexenes,heptenes, poteries, monenes, and the like, vup'fto about'ZO' carbon atoms being equally useful. That is, allof vthe normal mono olens having from 3 to 20 carbon atoms inclusive are useful and all of, the secondary and tertiary mono olens having from 5 to 20 carbon atoms, similarly being equally useful. (Isobutylene is not useable in this reaction since its high polymerization reactivity results in the polymerization of the isobutylene with a relatively very small amount of the multiolefin, yielding a wholly different, rubbery, type of substance, or a thick oil, not a hard resin.) Y

The preferred mixture is from 39% to 80% of the multi olefin, preferably butadiene because of its .cheapness and availability, with from '10% to 20% Vof di-lsobutylene, also because of its cheapness and availability. These materials are mixed, diluted with an appropriate amount of a diluent suchas liquid propane and polymerized by the addition of the appropriate catalyst.

Referringv to the "drawing, the butadiene is storedA in tank lv to whichit is delivered through a pipe 2 by a pump` 3, the suction of which is drawn from somesuch supply as a tank car. Simultaneously, the dimer is stored in a tank 4 after` receiptfromthe reiinery orother con-a venient, source. Preparatory` to use, the butadieneispassed through a calcium chloride dryer 5 and the dimer through a calcium chloride dryer 6. ,Bothdryers discharge .through a pipe 'I into the reactor 8.V ,The reactor contains a propeller Astirrer 9 which is driven by an appropriate motor (not shown). Simultaneously, a supply of ethyl chloride .is stored inthe container H, towhich it likewise. isdelveredfrom tank cars or other ,source of supply.v The ethyl chloride likewise is passedthrough a calcium chloride dryer l2 to one or the vother of mixing drums i4. From the mixing drums I4, the ethyl chloride is circulated through` an aluminumchloride dissolver' l5 by a pump .lli` until a sufciently strong solution of aluminum chloride is obtained in the drums I4.

Inthe meantima'. an appropriate amount of liquid propane isA delivered to the reactor 8 through a pipe line l1. The propane is volatilized by the warmth of the butadiene and dimer in the reactor 8 and passes upward through the pipe I8 to a reflux .condenser I9, -cooled with liquid ethylene deliveredthrough the supply pipe 2|. The reflux of c old propane iiows downward through the pipe 22, back into the reactor 8. This reflux cooling is continued until the ma- -terial is brought downto the desired temperature which is determined by the mixed boiling point of the contentsof the reactor, the amount of propane present being ,brought to a value such that the mixed boiling point is at the desired temperature. It may be noted that while liquid propane isiin some ways preferable, gaseous prolpane is useable,l since after introduction, it iS. 15.

4, cooled in the reflux condenser i9 and delivered as liquid through the pipe 22 to the reactor 8. When the desired temperature is reached, the catalyst is delivered by the pump 23 through pipe 24 to the reactor 8 in the form of a ne, highpressure jet which is very rapidly stirred into the olefin-containing mixture. The reaction proceeds promptly to yield the desired polymer resin. The rate of reaction is to a considerable extent determined by the rate of catalyst delivery, and the rate of delivery is preferably kept at a comparatively low value to avoid undue temperature rise in thereactor; that is, with a reactor containing 550 pounds of butadiene and'fl50 pounds of dimer dissolved in approximately| 790 pounds of propane, approximately '75 gallons of a 3% aluminum chloride solution in ethyl chloride are required for conversion of approximately of the oleflnic material; and this amount of catalyst ls deliveredover a time interval of approximately l to 2 hours.` When the reaction has reached the desired stage, a supply of light jnaphtha from the storage tank 25 is delivered by a pump 26 through a calcium chloride dryer 27 to the reactor 8 where it is Well stirred in by the stirrer 9. When a solution of the desired concentration has beenobtained by this means, a valve in the pipe 2l' is opened and the pump 28 drains the solution of polymer from the reactor 9 and delivers it to a wash tank 29 equipped with a stirrer 3i. Simultaneously, water from a tank 32 is delivered through pipe 33 to the washer 29. The wash Water is at a temperature considerably above the temperature of the polymerizate solution, and considerably above the boiling point of the ethyl chloride, the unreacted butadiene, and the propane. Accordingly, these components of the reaction mixture are volatilized out and discharged through an outlet pipe from the washer 29, Whereafter, they may be recovered, recycled and reused in subsequent polymerizations.

The pump 34 serves to circulate the wash water and polymer solution to obtain as complete a Ywashing as possible; at intervals the stirrer 3| is allowed torstop and the wash Water or wash solution is drained off and replaced by fresh water.

When the material has been washed sufficiently and has reached a condition of neutrality utilizing tom. This settling is comparatively slow and in a system having a height of 10 feet, 96%y of the gel will settle into the bottom v10 inches of the drum in approximately 30 hours. The settling is of course a function of both the'time and the density of the gel and simple settling beyond 8O hours usually does not yield sufficient additional clarification to justify additional settling. When the settling has proceeded to about this stage, the upper portion, the supernatant layer, is decanted off and transferred to a receiver Y6l. In this receiver, approximately one poundof filter aid such as a diatomaceous earth, sold as Hyflow Super Cell, per iivegallons of polymer solution is mixed in and very thoroughly and homogeneously stirred.

pumps .54 and B4 V fordeli-vering.liquids thereto. The iilter press is conveniently clothed with finetextured can-vas or with double' layers of blotting paper since single layers appear to lack suicient strength for `the pressure necessary.l .The suspension offiiiter aid is pumped into the `filter press -iirstgto.establish apre-coat Von the leaves of the presa When most lor the suspension. has been delivered to the nlter press, thevalves in the suction lines are changed, and thepolyrner solution containing the lter aid is delivered to the filter press under suiicient pressure to forcelitthrough the press. This pressure ranges between 40 pounds and 100 pounds per square inch, being .considerably less at -therbeginningoi a iltration than it is when the filtra-tion has been vcarried to .the stage where the amount of lter aid on the press plates is considera-ble. The clarified Asolution is then delivered to a receiving drum. 61, to which the pump 31 is connected and the clear polymer solution is delivered by. the pump 31 through a non-ferrous steam-jacketed pipe "systenute. v

This system consists of an inner pipe made of anon-ferrous material such as Monel metal or -nichromeor copper, or the like, or is .glass lined and. is surrounded by .a jacket of high .pressure .steam at from 105 to .250 pounds per `squareinch pressure. The polymer solution-delivered by the pump .371 into the innerpipe is rapidly .heated to a temperature 'abovev the melting point `of the resin, usually far enough above the-melting point to; leave the .resin in a relatively fluid form, and, accordingly, the rate of passage is quite rapid. To. facilitate complete removal of solvents from the resin, a stream of super-heated steam or inert Vgasis introduced into the coil-at a point where thetemperature of the. resin mass is above 212 F. (usually about midway of. the length of `the coil); this point being chosen in order that the temperature may be above the condensation point of water.

VThe steam serves as a stripping agent to carry forward and away as much as possible of the light .naphtha Instead of steam,.such substances as nitrogen, .carbon dioxide, clean. flue gas',-or other inert gaseous material which shows a low solubility in the polymer may be used.

It may be noted that even the best of Monel and nichrome alloys will contain from 2 to 6 or 7% u iron, .and some of this iron is' unavoidably absorbed by the resin. However, if the time of passage of the hot resin through the heater tube is less than four or ve minutes, the amount of iron picked up by the hot resin is less than about parts per million, which does not cause :a serious amount of discoloration.

From the exit end of the Monel pipe, the resin is discharged to a disengaginr drum 39 in which the molten resin is separated from the non-polymerized material at a temperature of approximately 280 F. From the drum 39 any residual, unpolymerized dimer and light naphtha added to the polymerizer to dilute the solution are driven oiT through the pipe 4| to the condenser 42. Simultaneously, the temperature in the receiver 39 is maintained by a steam coil 43 and by open steam from a distributor 44. In the condenser 42, the water, the dimer, and the added naphtha are condensed and delivered to a'receiver 45. The' water is drained out through a pipe 48 and sent to the sewer, and the naphtha, with small amounts of dimer, and so on, is drained out through the pipe 49 and returned by the pump 5| to the naphtha storage.

In the recovery of this copolymer resin it is essential that a relatively narrow .range of con= ditions yoftemperature and throughput through the coil must `be obtainedand these values are critical; thus., .if the rate of flow of the resin .solu`= tion through the coil is too low, or the temperatureis too low, the contact time is unduly long and the final resinis greenish in color or a dark brown, and not satisfactory for the manufacture of light-colored paints and varnishes; andif the rate of flow is too high incomplete separation occurs. Accordingly, the rate of flow and tempera turemust beadjusted according to the diameter and length of the pipe through which the resin solution flows so thatt-Lme is long enough and temperature high enough to free the solution from volatile components, and the rate of ow is fast enough and the temperature low enough to `prevent the contamination with iron to an extent suiiicient to discolor the resin. In the embodird ment herein, as above described, a Monel metal coil having a diameter of l inch and a length of ll0 feet `was used, surrounded with a steam jacket at a pressure of 105 lbs. per square inch.

inthe device and process above described, a

'substantial amount of light naphtha diluent is delivered directly tothe polymerizer, but with the reux condenser attached, the temperature does not rise above the boilingr point of the lowerboiling components, and accordingly, a very iiuid solution is delivered by the pmnp 23 to the washer 29. This method of operation is, however, not

` necessary. Instead, the pipe i8 leading to the reflux condenser maybe closedby a valve before the naphtha is introduced, and the naphtha may be warmed substantially' before being introduced. f

Under these circumstances, the light volatiles may be discharged through a pipe 2Q leading from the top of the reactor to a recovery and recycle system (not shown) by which the butadiene, the ethyl chloride, and the propane are separated by .a fractional distillation and stored in proper storage tanks for reuse. By this procedure, a somewhat heavier, more viscous solution is dei livered by the pump 29 to the washer 29, and substantially no light volatiles are disengaged in the washer. This procedure has som-e points of value in that itpermits of recovery and reuse of many of the components.; on the other hand, the cost o f equipment and power for the fractional distillation may, in some instances, amount to more than the value of the recovered materials.

In someinstances it is desirable to add to the resin various auxiliary substances such as other #types of resins or coloring bodies, such as oil soluble dyes, pigments, and the like. terials are readily added with the naphtha above Such madescribed; including such substances as natural rubber (Caoutchouc) isobutylenic polymers 'generally, the various dioleiinicY coepolymers, styrene,

either as a monomer or polymer, the co-polymers of styrene with isobutylene, the various allyl resins, the'various phthalate resins, the various vphenol-formaldehyde resins, and the like. Being added in solution, these resins are introduced in a very homogeneous mixture into the iinal product. It is'vof interest to note the surprising power of iron to degrade the color of this hydrocarbon type resin. The resin is wholly free from acid `sub=` stituents and should be wholly non-corrosive. Nevertheless, at high temperatures, its attraction for traces of iron` `is phenomenally and unex= pectedly high,.to such an extent that it cannotbe processed readily inv iron equipment, even stainlesssteel, without a serious or fatal contamina= tion by iron Which, in amounts above about 100 parts per million, yields a deep yellow color, and, in amounts above 1000 parts per million, yields a brown, opaque resin. Accordingly, the process of the present invention washes out the iron, aluminum and similar material as carefully as possible to bring the resin solution to a closely neutral condition, and then removes the solvent by a heat treatment in the absence of ferrous structures to maintain as low an iron content as possible.

Per Cent Fe (based on oil) Color EXAMPLE 1 A mixture consisting of 55 parts of butadiene with 45 parts of di-isobutylene was polymerized as above outlined in the presence of appropriate diluent, and delivered to the drum 35 along with a suitable amount of an appropriate light solvent naphtha. The mixture was allowed to settle, as above outlined, for approximately 12 hours, during which time residual traces of water settled out and a considerable portion of the insoluble cross-linked gel settled to the bottom. The partially clarified supernatant liquid was then drawn off by the pump 64 and delivered to the drum 6| in which it was mixed with approximately 1 lb. of filter aid, per five gallons of resin solution. The mixture was then transferred to the drum B2 in which it was kept in continual agitation to prevent the filter aid from settling out. As a preliminary to this procedure, a substantial portion of lter aid was suspended in clear naphtha, added to the drum 6I and delivered by the pump 64 directly to the-filter press 63 through the appropriate pipe connections shown by suitable adjustment of the valves. This procedure when conducted, put on the filter plates a pre-coat of filter aid. When the pre-coat was formed, the resin solution and the suspended filter aid were delivered by the pump 64 to the filter press 63 and the filtrate collected in the receiver 61, from which it was delivered by the pump 31 to the finishing coil as above outlined.

A series of runs were made without and with filter aid, and without and with filter aid precoat on the press leaves. In each instance, the

filtration rate in gallons per hour, per square r foot was determined. The results-are recorded in the following Table 1:

Table 1,

serious discoloration. The effect of iron is well shown in the following Table 2:

Table 2 0.01 0. 007v 0.005 0. 004 0. 003 0. 002 0. 001 0.0001 11-18 17 1e is 14 14 s 7 Thus it is apparent that greater than 0.001% Fe is harmful.- The fact that the resin produced by this process shows a Gardner color of 1l indicates that there is present not much more than 0.001% of iron in the finished resin.

` Alternatively, the filter 63 may be replaced by a centrifuge as shown in Fig. 2. For this purpose the polymer may be delivered to the tank 35 and the Water settled out as before described. The settling may be continued sufficiently long lto settle out a major portion of the gel, or the settling tank 35 may be used merely to settle out traces of water. Then either the partially clarified supernatant liquid or the entire solution is sent to a centrifugal separator.

The centrifugal separator may preferably beta basket type, having an appropriate lining, such as a canvas bag into which the resin solution is delivered. The resin may be sent to the centrifuge directly from the settling tank 35 or an appropriate amount of filter aid may be incorporated in the solution as was done for the filtration process above described. It may be noted that a good centrifuge gives a much higher effective pressure and accordingly smaller amounts of filter aid may be used and a considerably higher filtration rate per square foot of filter surface may be obtained. Also the combination of larger basket, smaller quantities of filter aidand higher driving pressure permits clarification of considerably larger quantities of resin solution before it becomes necessary to suspend operations for the removal of the separated gel.

The clarifying material from the centrifuge may be delivered to a similar receiver 5i and Y then transferred to and through the finishing coil 30 by the pump 3'! as above outlined. Alterna- Filter Aid Preeoat Filter Aid Per Cent Y Filter Rate.

Press. Drop,

` GalJhn/sq. ft.

None Super FiltroL Do Filter Cel charge) These results show a very great increase in filtration rate in the presence of the filter aid. In addition, the presence of the filtration aid greatly increased the number of gallons of polytively a bowl type centrifuge of the cream separa?- tor type may be used by which a stream of highly `clarified polymer solution is taken from the center outlet and a stream of solution containing f1 9 a relatively high concentration of gel is taken from-the side outlet. These two streams are separately collected, the claried stream being sent to the `filtrate receiver 6? for hashing, the gel concentrate being discarded or mixed with i'ilter aid and iiltere'dy lby a procedure similar to that above outlined, if it is desired to recover all of the soluble polymers.

Alternatively, -the polymer may be clarified by percolation through a lter bed as shownA in Figure 3, in which case also it is preierably pre-settled'to remove as much as'possible or the gel, in the receiver 35 and the supernatant liquid is decanted oi and passed through the percolating filter 1l. 'I'his filter may contain a layer at the bottom of lter material I2 in the form or" active clay or carbon black, or diatomacecus earth as desired. The polymer solution percolates through the filter layer and collects in the bottom of the iilter tank 12 from which it is conveniently drained to a receiver 13. From the receiver i3, the clarified liquid is drawn by the pump 37 and delivered to the flash coil 38 as above outlined.

The concentrate of insoluble gel is useless for paint and varnish purposes. However, it contains a substantial amount of dissolved polymer.

This polymer can be recovered by the steps or"y diluting the material whether it contains lter aid or not and reiiltering. The percolating iilter is readily stripped of substantially all or" the soluble gel by the addition of substantial amounts of wash naphtha, and the material on the iilter Vplates can also be freed substantially clear from soluble polymer by washing with naphtha. It is possible to use the high gel concentrate with or without the lter aid, as a molding composition, preferably with additional amounts of pigment or filter. For this purpose, such substances as lamp black, clay, Whiting, barytes, Zinc oxide, chrome green, chrome yellow, rouge, ground cork,

Wood flour, and the like may be added to produce Y a molding composition of the desired consistency which, in pressure molding, yields an excellent molded article, since the soluble polymer remaining is readily cross linked by heat into a hard, insoluble, infusible gel. In the preparation of such a molding composition it is usually desirable to add the additional pigment to the more or less fluid solvated gel, stir or mix to a homogeneous composition and then evaporate out the volatile solvent to leave behind unsolvated gel and sola vent-free polymer since in this condition a better molding resin is obtained.

Thus the process of the invention polymerizes a mixture of mono oleiin and multi olefin to a hard resin, while in solution, and removes from that solution all of the solvated, insoluble cross-linked material to leave a clear, sparkling, nearly white, solid resin by such steps as prolonged settling or filtering in the presence of a lter aid or by percolation filtration or by centrifuging; and yields as a by-product a mixture of gel, soluble resin, and pigment which is highly suitable for mold ing compositions.

While there are above disclosed but a limited number of embodiments of the process and apparatus of the present invention, it is possible to produce still other embodiments without departing from the inventive concept herein disclosed and it is therefore desired that only such limitations be imposed on the appended claims as are stated therein or required by the prior art.

The invention claimed is:

1. In a copolymerization process for the production of a clear, light-colored resin solution l0 essentially free of cross-flinked geltimpurity, the steps in combination which compriseadmixing from 30 to 80 parts'by weight'of butadieneyw'ith from 70 to 20A parts by weight 'of diisobutylene, diluting the'niixture with liquid propane, cooling the mixture to a temperature within the range between |10 C. merising. the resulting mixture by the addition thereto of a solution of aFriedel-Crafts catalyst comprising 3% by. weightof aluminum chloride in solution in ethyl chloride, maintaining the reaction temperature within the range of +10 C. to 30 C. by continuous yreturn of liquid propane reflux to the reaction mixture, whereby there is produced a solution of butadiene-diisobutylene copolymer in propane and unpolymerized monomers together with cross-linked gel impurity, admixing said solution of copolymer with suicient solvent naphtha to produce a fluid solution, water-washing the resulting iluid solution to remove catalyst and neutralize the solution, settling the iiuid solution to separate water and at least a part of cross-linked gel impurity from the solution of copolymer in solvent naphtha, separating the solution of copolymer in solvent naphtha, adding a filtering aid to said settled and decanted polymer solution, and ltering the settled and decanted polymer solution-by the assistance of the lter aid to remove substantially all the remaining cross-linked gel impurity, whereby there is produced a clear copolymer solution having a Gardner color value of at least 7.

2. In a copolymerization process for. the production of a clear, solid, light-colored resin essentially free of cross-linked gel impurity, the steps in combination which comprise admixing 55 parts lby weight of butadiene with 45 parts by weight of diisobutylene, diluting the mixture with liquid propane, cooling the mixture to a temperature of approximately 30 C., copolymerizing the resulting mixture by the addition thereto of a solution of a Friedel-Crafts catalyst comprising 3% by weight of aluminum chloride in solution in ethyl chloride, maintaining the reaction temperature at approximately 30 C. by continuous return of liquid propane reflux to the reaction mixture, whereby there is produced a solution of butadiene-diisobutylene co=A polymer in propane and unpolymerized mono mers together with cross-linked gel impurity, admixing said solution of copolymer with suffi cient solvent naphtha to produce a fluid solution, water-washing the resulting fluid solution to remove catalyst and neutralize the solution, settling the uid solution to separate water and at least a part of cross-linked gel impurity from the solution of copolymer in solvent naphtha, separating the solution of copolymer in solvent naphtha, adding a iiltering aid to said settled and decanted polymer solution, filtering the settled and decanted polymer solution by the assistance of the lter aid to remove substantially all the remaining cross-linked gel impurity, and volatilizing the light solvent naphtha from the butadiene-diisobutylene copolymer by passing the filtered polymer solution through a heated pipe made of non-ferrous material, whereby there is produced a clear, solid copolymer having a Gardner color value of at least 7.

JOHN D. GARBER. DAVID W. YOUNG.

(References en following page) 12 REIPEREIMJI;Sy CITED Number Name Date, The following references are Qf record in the 2356'128 Thomas Aug' 22 1944 le of this patent!" pars 3131"" g' UNT En STATES PATENTS par ,s y

5 OTHER REFERENCES Number Name Date 1,982,708 Thomas Dem 4, 1934 ThOmaSZ Ind. Eng. Chem., 24, 1125-1128 OC- 2,1s7,e2'1 Reed Nov. 22, 193s tober 1932 Y 2,142,980 Hunger Jan. 3, 1939 Kolthff and Sanden: Textbwkf Quantita- 216094 Britton s813224, 1940 m tive Inorganic Ana1ysis; m2122316, Macmillan. 2,258,268. sparks oct. fz, 1941 N- Y- 1943)- 2273158- Thomas Feb. 17 1942 Sbrell: Ind. Eng. Chem. 35, 73491-40 (1943). 

1. IN A COPOLYMERIZATION PROCESS FOR THE PRODUCTION OF A CLEAR, LIGHT-COLORED RESIN SOLUTION ESSENTIALLY FREE OF CROSS-LINKED GEL IMPURITY, THE STEPS IN COMBINATION WHICH COMPRISES ADMIXING FROM 30 TO 80 PARTS BY WEIGHT OF BUTADIENE WITH FROM 70 TO 20 PARTS BY WEIGHT OF DIISOBUTYLENE, DILUTING THE MIXTURE WITH LIQUID PROPANE, COOLING THE MIXTURE TO A TEMPERATURE WITHIN THE RANGE BETWEEN +10* C. AND -30* C., COPOLYMERIZING THE RESULTING MIXTURE BY THE ADDITION THERETO OF A SOLUTION OF A FRIEDEL-CRAFTS CATALYST COMPRISING 3% BY WEIGHT OF ALUMINUM CHLORIDE IN SOLUTION IN ETHYL CHLORIDE, MANITAINING THE REACTION TEMPERATURE WITHIN THE RANGE OF +10* C. TO -30* C. BY CONTINUOUS RETURN OF LIQUID PROPANE REFLUX TO THE REACTION MIXTURE, WHEREBY THERE IS PRODUCED A SOLUTION OF BUTADIENE-DIISOBUTYLENE COPOLYMER IN PROPANE AND UNPOLUMERIZED MONOMERS TOGETHER WITH CROSS-LINKED GEL IMPURITY, ADMIXING SAID SOLUTION OF COPOLYMER WITH SUFFICIENT SOLVENT NAPHTHA TO PRODUCE A FLUID SOLUTION, WATER-WASHING THE RESULTING FLUID SOLUTION TO REMOVE CATALYST AND NEUTRALIZE THE SOLUTION, SETTLING THE FLUID SOLUTION TO SEPARATE WATER AND AT LEAST A PART CROSS-LINKED GEL IMPURITY FROM THE SOLUTION OF COPOLYMER IN SOLVENT NAPHTHA, SEPARATING THE SOLUTION OF COPOLYMER 